User Manual

Table Of Contents
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7
Therapeutic and Diagnostic Functions
Diagnostic functions
Data from implantation and the most recent interrogations and follow-ups are
recorded as well as arrhythmia episodes; they are stored together with other data
to assess both the patients' and the device's state at any time.
To check the lead for proper functioning, an automatic impedance measurement
using subthreshold pacing pulses is performed in the device.
Leadless ECG function: For all device types, far-field derivation can be measured
without external leads between the right ventricular shock coil and housing, which,
depending on the implantation site, corresponds to ECG derivation II or III
(Einthoven).
Once a telemetry connection has been established during a test procedure in
an in-office follow-up, the leadless ECG and the IEGM are displayed with markers.
Antitachycardia pacing
The ICD can treat ventricular tachycardia with antitachycardia pacing (ATP); ATP
can also be delivered in the VF zone (ATP One Shot) when the stability criterion
(monomorphic rapid VTs) is met before shock delivery.
The ICD can also respond to atrial tachycardia with antitachycardia pacing (ATP) in
case of stable heart rates or with high-rate pacing (HF bursts) in case of unstable
heart rates.
Depending on the device type, the device program contains not only the ICD
functions but also all pacemaker functions for 1, 2 or 3 chambers. The heart rhythm
is continuously monitored; each arrhythmia is classified according to the heart rate
and the adjustable detection criteria. Depending on the preset values, antibrady-
cardia as well as antitachycardia therapy is inhibited or delivered.
Cardioversion, defibrillation
The ICD can treat ventricular tachyarrhythmia with cardioversion and/or defibrilla-
tion. Shock polarity and energy can be programmed individually. Shock energies
between 2.0 J and 40 J are possible. Before delivery of the shock, the ICD can be set
to only deliver a shock when ongoing tachyarrhythmia is confirmed; during this
time period the device can identify spontaneous conversion of the tachyarrhythmia
and cancel the charging process if necessary.
The shock paths can be set between the different shock coils (SVC/RV) and/or the
housing.
Antibradycardia pacing and CRT
Rate hystereses, automatic sensor functions, and a night program promote the
patient's intrinsic rhythm, avoid overdrive pacing, and facilitate adaptation of the
device to the individual needs of the patient.
Both atrial and ventricular thresholds are determined automatically in the device.
For the 5 and 7 series , capture control is used to set the pulse amplitudes so that
pacing is performed with the optimum atrial and ventricular amplitude for the
patients with each change of the pacing threshold.
Setting an upper tracking rate for the atrium prevents unspecific atrial pacing, thus
reducing the risk of pacemaker-mediated tachycardia.
Positive AV hysteresis functions support intrinsic conduction and thus the natural
contraction sequence. Negative AV hysteresis functions support the cardiac resyn-
chronization therapy by maintaining pacing in stress situations.
For resynchronization of the ventricles, triple-chamber implants have functions for
multisite pacing with possible VV delays in either direction.
To ensure that no additional surgery is necessary in case of a left-sided increase of
pacing threshold or undesired phrenic nerve stimulation, different pacing polarities
can be set for the left ventricular lead with a triple-chamber device. Up to
12 vectors can be used with the HF QP device type.
With the HF QP device of the 7 series: Two stimuli can be configured for the left
ventricle with a view to improve the resonchronization of the ventricles. The stimuli
can be delivered sequentially or simultaneously.
Additional, special form of rate adaptation with devices from the 7 series: an
increased cardiac output requirement is detected using physiological impedance
measurement. The measuring principle is based on contractile changes (ionotropy)
of the myocardium (CLS function: Closed Loop Stimulation). Rate adaptation is
automatically initialized and optimized in CLS mode.
Ventricular pacing suppression with devices from the 5 and 7 series unnecessary
ventricular pacing is avoided by promoting intrinsic conduction (Vp suppression
function). The device can thereby adapt to conduction changes and switch between
an ADI(R) and a DDD(R) mode.
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